This invention is intended to determine the property of coals in a simple and expedite manner by measuring the distribution of reflectance of the coals.
The term "coals" herein used includes a coal ranging from brown coal to anthracite; a solid hydrocarbon derived from the material of the coal or petroleum system; and carbonized remains of fossil plants contained in a sedimented rocks; and the like.
The coals will change to various hydrocarbon compounds, depending upon the material from which they originate and by the metamorphism action of heat, pressure and time. As a result, they will have various properties. In an attempt to measure this change quantitatively, it has been proposed to measure the content of C, H and O by elementary analysis or to measure the volatile matter by approximate analysis.
However, a natural coal or a solid hydrocarbon technically derived therefrom is generally a mixture of the various compounds, and it is thus difficult to grasp the property of such coals based only upon the average value of analysis.
Recently, an attempt has been made to measure the optical reflectance of coals to overcome the above disadvantage. It is based on the fact that some particular component in the coals has a property to increase the optical reflectance in proportion to the degree of metamorphism, and that the degree of the metamorphism or coalification can thus be determined by measuring the optical reflectance of the particular component.
To know the degree of coalification is not only significant to judge the coking property of the coking coal in coke industry but also helpful in studying correlation of strata in geology or prospecting petroleum by measuring the degree of metamorphism given to strata.
In measuring the reflectance of coals for the above purpose, it has heretofore been a practice to use a photometer attached to a microscope and manually operate the same. Generally, the natrual coals include many kind of hydrocarbons. It is therefore more significant to know the distribution of reflectance rather than to measure the reflectance per se, which will necessitate measuring of reflectance at as many points as possible. Such measuring by manual operation needs a great deal of time and labor, so that the measuring at only 50 to 100 points in one sample has been the maximum. It is of course not sufficient to give a satisfactory result in a practical use. For example, in judging the coking property of the coal, it has heretofore been a practice to conduct such measuring at 50 to 100 points by first carring out the Maceral analysis and then measuring the number of the Vitrinit part in the sample. It takes a lot of time and labor as mentioned above and is thus not efficient. Consequently, an automatic measuring device has been developed to improve accuracy and cut labor by increasing the measuring speed and the number of the measuring points. However, in view of the fact that the reflectance of the coals is as small as about 1% of the incident light thereto and that a clear solution has not been made yet as to the relation between the distribution of the reflectance of the coals and the property thereof, etc., a completely satisfactory apparatus has not been obtained yet, although it is still quite important to know such property of the coals.
For example, in an iron making industry, a great deal of coke is used. In this case, it is extremely useful for presuming the strength of the product coke to judge the coking property of the material coal. It is particularly necessary, where various material coals are imported from various countries, such as in the iron making industry in Japan, for investigation of the quality of the coal imported from the undeveloped coal mine for quality control of the coal imported, or for optimum coal blend, etc. Conventionally, many tests such as approximate analysis, elemental analysis, measuring of fluidization, test as to softening and expanding, measuring of coefficient of bonding power and so on have been proposed, all of which have proved to be insufficient for the practical operation. Furthermore, coking in the test furnace or testing in the practical oven, etc. have been conducted with a lot of time and labor, but a satisfactory result could not be obtained. Under these circumstances, a theory based upon the coal structure that there is a possibility of presuming the strength of the coke by the analysis of the petrographical constituents of the coal and by the measuring of the reflectance of the Vitrinit in the coal has recently been proposed, a part of which has been practised in various countries. This method is being utilized for the investigation of the quality of the coal of the undeveloped coal mine or for the quality control of the coal imported, since it has advantages that the coking property of the coal can be determined with small amount of samples, that the strength of the coke given when many kind of material coals are mixed can be calculated, and that the oxidized coal and the mixed coal can be discriminated, etc. Based upon the theory of the coal histology, the main factor upon which the strength of the coke depends is considered to be (a) the ratio of the component which will melt to the component which will not melt and (b) the bonding power of the component which will melt, when the coke is produced by dry distillation of the coal. It is also known that the bonding power varies with the degree of coalification of a coal can be reasonably expressed in term of the reflectance of the Vitrinit which is the chief component of the coal. It has conventionally been practised, however, to discriminate the components of the coal by the visual power of the operator depending upon its reflectance, optical anisotropy, optical property such as form, hardness, etc. to measure 500 points or more by the point count method and measure 100 points or more of the maximum reflectance of the Vitrinit component in the coal. As a result, it takes about three hours to measure one sample, which is not efficient and gives rise to incur personal errors resulting from the visual operation of the operator.
Accordingly, the value of the strength of the coke derived from the above result is not always reliable. In other words, this method is theoretically correct but the result obtained is not always correct for the reasons that the sample error is unavoidable because of limitation of the number of measuring points and that the personal error is also unavoidable because of the subjectivity of the operator who effects the visual observation by microscope.
Table 1 __________________________________________________________________________ The petrographical analysis compared with the automatic and manual method Joint Test by domestic Test by I.C.U.P. eight companies 28 companies Sample Max. Min. Average Average Deviation Manual Test A % % % % % I% II% __________________________________________________________________________ Vitrinit 79.5 61.5 68.4 68.6 6.3 70.8 69.2 Exinit 16.2 10.1 13.3 12.2 6.4 9.2 10.8 Inertinit 19.4 14.3 16.1 17.0 2.7 17.8 17.8 Mineral 2.2 2.2 2.6 2.1 2.2 2.1 1.2 Matter (0.6) (0.6) Mean Reflect- 0.78 0.73 0.75 0.76 0.03 ance (*525) Mean Reflect- 0.66 0.05 0.67 0.68 ance (*546) Sample B Vitrinit 65.5 45.1 53.0 48.7 7.7 55.3 53.3 Exinit 3.6 0 0.8 0.3 0.9 0.6 0.5 Inertinit 49.5 29.8 41.5 47.2 7.9 40.0 42.0 Mineral 4.1 4.1 5.4 3.0 4.1 3.8 2.0 Matter (0.1) (0.1) Mean Reflect- 1.38 1.24 1.30 1.29 0.05 ance (*525) Mean Reflect- 1.15 0.05 1.15 1.15-ance (*546) Sample C (A30% + B70%) Vitrinit 65.8 53.2 59.4 57.6 56.6 50.7 Exinit 6.7 2.8 4.7 4.6 2.8 6.1 Inertinit 37.6 25.7 31.7 33.9 36.4 39.0 Mineral Matter 4.5 3.9 4.2 3.9 4.2 4.2 Mean Reflect- 1.20 1.08 1.12 1.12 0.04 ance (*525)-Mean Reflect- 0.98 0.03 1.00 0.98 ance (*546) __________________________________________________________________________ Note: (1) Figures parenthesized are amount of pyrite included. (2) *is wave length (.mu.m) of filter.
Table 1 shows the result of tests conducted at 28 places in the world regarding the same three samples. From this it can be observed how the measuring error is large.
In order to overcome the above defect, the automatic operation of the analysis of the structure has been proposed. For example, there have been developed a method to determine the ratio of each component in a coal by strictly dividing the voltage issued from the photoelectric tube attached to the microscope by utilizing the phenomenon that said structual components have respectively increased reflectances in the order of Exinit, Vitrinit, Inertinit and Pyrite, and a method to cause the computer to memorize directly the output issued from the photoelectric tube attached to the microscope so as to automatically measure the coking property based on the average value of said output by utilizing the phenomenon that the reflectance of the coal changes as the degree of coalification of the coal progresses, etc.
Examples of such literatures are (1) "Determination of proportions of coal components by automated microscopic reflectance scanning" by J. T. McCartney et al in Fuel, Vol. 50 (1971) p226 to 234 and (2) "The development of automatic analysis equipment at the coal research establishment of the national coal board" by J. A. Harrison et al in Proceeding of the Conference on Laboratory Automation I.E.R.E., London, Nov. (1970) 345 page.
However, these methods mentioned above may be useful to a particular kind of coal but are not so adaptable as presuming the coking property of every kind of coals.
The minimal necessary factor for judging the coking property of the coal is to know (a) the degree of coalification of the material coal and (b) the ratio of the component which will melt (hereinafter referred to as "reactives") to the component which will not melt (hereinafter referred to as "inerts") during the coking. Generally, the reflectance of the "inerts," except for its ash value, is higher than that of the "reactives". On the other hand, there is a phenomenon that the reflectance of the "reactives" becomes higher as the degree of coalification progresses. Accordingly, there is considerable difficult caused when the degree of coalification and the amount of the "reactives" are simultaneously determined only by the reflectance. It is because there exist both the "inerts" and the "reactives" in the component having the same reflectance.